VMS Help V73 Features, Programming Features, Compaq C Run-Time Library Enhancements  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The following sections describe the Compaq C RTL enhancements
    included in OpenVMS Version 7.3. For more details, refer to the
    revision of the Compaq C RTL Reference Manual that ships with
    Compaq C Version 6.3 or later.

1 - Strptime Function Is XPG5-Compliant

    The strptime function has been modified to be compliant with
    X/Open CAE Specification System Interfaces and Headers Issue
    5 (commonly known as XPG5). The change for XPG5 is in how the
    strptime function processes the "%y" directive for a two-digit
    year within the century if no century is specified.

    When a century is not otherwise specified, XPG5 requires that
    values for the "%y" directive in the range 69-99 refer to years
    in the twentieth century (1969 to 1999 inclusive), while values
    in the range 00-68 refer to years in the twenty-first century
    (2000 to 2068 inclusive). Essentially, for the "%y" directive,
    strptime became a "pivoting" function, with 69 being a pivoting
    year.

    Before this change, the strptime function interpreted a two-digit
    year with no century as a year within twentieth century.

    With OpenVMS Version 7.3, XPG5-compliant strptime becomes a
    default strptime function in the Compaq C RTL. However, the
    previous nonpivoting XPG4-compliant strptime function is retained
    for compatibility.

    The pivoting is controlled by the DECC$XPG4_STRPTIME logical
    name. To use the nonpivoting version of strptime, either:

    o  Define DECC$XPG4_STRPTIME to any value before invoking the
       application.

       OR

    o  Call the nonpivoting strptime directly as the function
       decc$strptime_xpg4.

2 - Nested Directory Levels Limitation Lifted (Alpha)

    The Compaq C RTL I/O subsystem was enhanced to remove the
    restriction of eight nested directory levels for an ODS-5 device.
    This affects Compaq C RTL functions such as access, mkdir,
    opendir, rmdir, and stat.

3 - Improved Support for Extended File Specifications (Alpha)

    The following sections describe improved Compaq C RTL support for
    extended file specifications.

 3.1 - Case Preservation

    Programs linked against the Compaq C Run-Time Library DECC$SHR
    can now preserve the case of file names on ODS level 5 disks.
    This applies when creating or reporting file names. By default,
    this feature is disabled. To enable this feature, enter the
    following command:

    $ DEFINE DECC$EFS_CASE_PRESERVE ENABLE

    If file names are all in uppercase, use the following command to
    convert the names to lowercase when reporting the name in UNIX
    style:

    $ DEFINE DECC$EFS_CASE_SPECIAL ENABLE

    If file names are not all in uppercase, then DEFINE DECC$EFS_
    CASE_SPECIAL ENABLE preserves case.

    The commands to disable the preceding logical-name settings are:

    $ DEFINE DECC$EFS_CASE_PRESERVE DISABLE
    $ DEFINE DECC$EFS_CASE_SPECIAL DISABLE

    The setting for the DECC$EFS_CASE_SPECIAL logical name, if not
    set to DISABLE, supersedes any setting for the DECC$EFS_CASE_
    PRESERVE logical name.

    The DECC$EFS_CASE_PRESERVE and DECC$EFS_CASE_SPECIAL logicals
    are checked only once per image activation, not on a file-by-file
    basis.

 3.2 - Long File Names

    For OpenVMS Alpha Version 7.2, some basic Compaq C RTL I/O
    functions (creat, stat, and the functions from the open family
    of functions) were enhanced to accept long OpenVMS-style file
    names for an ODS-5 device.

    For OpenVMS Alpha Version 7.3, all other Compaq C RTL functions,
    except chdir and the functions from the exec family of functions,
    were also enhanced to accept long OpenVMS-style file names for an
    ODS-5 device.

    All C RTL functions that accept or report full file
    specifications will process file specifications up to 4095 bytes
    long, subject to the rules defined for the media format. For
    file specifications in OpenVMS format, there are no special
    restrictions. In situations where a full file specification
    cannot be reported because the buffer is too short, the function
    attempts to report the abbreviated name.

    UNIX file names have the following restrictions:

    o  Names containing special characters, such as multiple periods,
       caret, or multinational characters, may be rejected.

    o  A function call may report failure if the output buffer is
       not large enough to receive the full name. For OpenVMS style
       names, the reported name would contain a file ID-abbreviated
       name. There is no representation of file ID-abbreviated names
       defined for UNIX.

4 - Exact Case Argv Arguments (Alpha)

    Nonquoted command-line arguments passed to C and C++ programs
    (argv arguments) can now optionally have their case preserved,
    rather than being lowercased as in previous versions.

    By default, this feature is disabled.

    To enable this case preservation feature, define the logical
    name DECC$ARGV_PARSE_STYLE to "ENABLE" and set the process-level
    DCL parse style flag to "EXTENDED" in the process running the
    program:

    $ DEFINE DECC$ARGV_PARSE_STYLE ENABLE
    $ SET PROCESS/PARSE_STYLE=EXTENDED

    Enabling this feature also ensures that the image name returned
    in argv[0] is also case-preserved.

    To disable this feature, use any one of the following commands:

     $ SET PROCESS/PARSE_STYLE=TRADITIONAL

    or

    $ DEFINE/SYSTEM DECC$ARGV_PARSE_STYLE DISABLE

    or

    $ DEASSIGN DECC$ARGV_PARSE_STYLE

    The value of the DECC$ARGV_PARSE_STYLE logical is case-
    insensitive.

5 - Implicitly Opening Files for Shared Access

    The Compaq C RTL was enhanced to open all files for shared access
    as if the "shr=del,get,put,upd" option was specified in the open*
    or creat call.

    To enable this feature, define the logical name DECC$FILE_SHARING
    to the value "ENABLE". The value is case-insensitive.

    DECC$FILE_SHARING is checked only once per image activation, not
    on a file-by-file basis.

6 - Translating UNIX File Specifications

    The Compaq C RTL was enhanced to allow interpreting the leading
    part of a UNIX-style file specification as either a subdirectory
    name or a device name.

    The default translation of a "foo/bar" UNIX-style name to a
    "foo:bar" VMS-style name remains the default.

    To translate a "foo/bar" UNIX-style name to a "[.foo]bar" VMS-
    style name, define the logical name DECC$DISABLE_TO_VMS_LOGNAME_
    TRANSLATION to ENABLE.

    DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION is checked only once per
    image activation, not on a file-by-file basis.

7 - New Functions

    The Compaq C RTL has added the following functions in OpenVMS
    Version 7.3:

    fchown
    link
    utime
    utimes
    writev